The role of backscattered energetic atoms in film growth in reactive magnetron sputtering of chromium nitride

Abstract

In this work the impact of backscattered energetic atoms on film growth in reactive sputtering of CrNx (x _ 1) is manifested. We use film and plasma characterization techniques, as well as simulations in order to study the dynamics of the target–discharge–film interactions. The results show that the primary bombarding species of the growing film are N+2 plasma ions, which are neutralized and backscattered by the target in the form of atomic N. It is shown that the backscattered N atoms have energies which are significantly higher than those of other bombarding species, i.e. the backscattered Ar atoms, the sputtered atoms and the plasma ions. Moreover, it is found that CrN films exhibit compressive stresses of 2.6 GPa and a density close to the bulk value. We attribute these properties to the bombardment by backscattered energetic atoms, in particular N. Pure Cr films are also studied for reference.